1. Field of the Invention
This invention generally relates to a display device and, more particularly, to a barrier 3D display and a driving method for a barrier device.
2. Description of the Related Art
Along with the maturity of the liquid crystal display (LCD) technology, various portable electronic devices generally adopt a liquid crystal display to increase the practicability thereof. In order to further increase the operational convenience of the portable electronic device, the liquid crystal device adopted in the portable electronic device can display in two directions; in other words, even the portable electronic device is rotated between portrait and landscape views, the operation direction of the liquid crystal display is also rotated simultaneously to allow the user to see images normally. Meanwhile, as the 3D display is gradually becoming popular, in addition to the household display having 3D display function, the portable electronic device such as the cell phone, PDA and notebook may adopt a 3D display to increase the pleasure of electronic products.
A conventional 3D display generates left-eye image signals and right-eye image signals having perpendicular polarization directions within different time intervals such that a user can see 3D images only by using polarization glasses. However, the use of the polarization glasses is inconvenient. Therefore, the field provides a 3D technology to separate left-eye images and right-eye images by using a parallax barrier such that the use of the polarization glasses is no longer necessary.
FIG. 1 shows a conventional parallax barrier 9 for 3D display. The parallax barrier 9 includes an upper substrate 91 and a lower substrate 92 disposed oppositely, and a liquid crystal layer 93 sandwiched between the upper substrate 91 and the lower substrate 92. The upper substrate 91 includes an upper glass substrate 911 and an upper transparent electrode 912 formed on the whole surface of the upper glass substrate 911. The lower substrate 92 includes a lower glass substrate 921 and a plurality of lower transparent electrodes 922 arranged in parallel on the lower glass substrate 921. When a potential difference is provided between the upper transparent electrode 912 and the plurality of lower transparent electrodes 922, liquid crystal molecules in alignment between the upper transparent electrode 912 and the plurality of lower transparent electrodes 922 will be rotated to stop the light from penetrating whereas liquid crystal molecules not disposed between the upper transparent electrode 912 and the plurality of lower transparent electrodes 922 do not rotate. In other words, liquid crystal molecules disposed between the upper transparent electrode 912 and gaps between the plurality of lower transparent electrodes 922 do not rotate (i.e. normally white state). In this manner, when a user watches toward the parallax barrier from the upper side of the upper substrate 91 (the light is assumed incident from the lower side of the lower substrate 92 herein), the user is able to see transparent areas and opaque areas arranged alternatively.
When the pixels of a display are designed to have left-eye pixels and right-eye pixels and the parallax barrier 9 is disposed in front of the display, two eyes of a user can watch different image signals through the transparent areas of the parallax barrier 9 such that the user can see 3D images. However, the 3D display adopting the parallax barrier 9 can show 3D images in one direction and thus is not suitable for portable electronic devices capable of displaying in two directions.
Accordingly, it is necessary to provide a 3D display capable of displaying 3D images in two directions (i.e. portrait and landscape modes).